1. Field of the Invention
This invention relates to an apparatus and procedures for growing cells or tissue culture in vitro and more particularly to a culture vessel assembly having means for varying the gas diffusion rate into and out of the assembly and for substantially minimizing biological contamination of the cells or tissue culture in the assembly.
2. Description of Related Art
Culture vessels are described in U.S. Pat. Nos. 4,495,289, 5,026,649, 5,358,871 and 5,366,893 and European Patent Application No. 0 483 620 A2 and U.K. Patent Application No. GB 2 268 187 A. Culture vessels comprise wells which generally have a circular shape and size which permits the introduction therein of a cell culture insert having a membrane upon which cell attachment, growth and differentiation occur. The culture vessels containing the wells are typically rectangular and have a standard size in order to accommodate standard analytical apparatus. Cell culture inserts used in culture vessels are described in U.S. Pat. Nos. 4,871,674, 5,026,649 and 5,366,893 and are herein incorporated by reference.
The culture of cells is dependent upon the ability to supply sufficient oxygen to the cells without causing cellular damage. The supply of oxygen for cell respiration is from the atmosphere in the header space above the cells via the liquid culture medium.
Aeration of the culture, by for example, sparging, surface aeration, medium perfusion, can increase the oxygen availability, however such methods can cause cellular damage. Silicone rubber tubing has been used to improve gas exchange in cell culture, by running the tubing between the well and the atmosphere, but this method is inconvenient and may cause contamination to the cell suspension.
Although there are a number of culture vessels commercially available and described in patent publications, it is believed that there are no culture vessels available that provide a means for varying the gas diffusion rate into and out of a culture vessel assembly while still providing a closed system whereby entry or exit of biological contaminants into or out of the vessel is substantially minimized.